Monitoring and Quantification of Total Coliforms, Fecal Coliforms and Escherichia Coli, in Seven Micro-basins of Lake Amatitlán

Abstract

Monitoring and diagnosis of the current situation of bacterial contamination was carried out in seven micro-basins of Lake Amatitlán (San Lucas River, Zanjón La Palín, Zanjón El Zacatal, Quebrada del Frutal, Chanquín River, Pinula River and Guadrón River). Biological indicators associated with fecal matter, such as the coliform group, were used. The quality of the existing water in the micro-basins was analyzed and quantified for total coliforms, fecal colliferomes and Escherichia coli. The procedure used for the initial isolation was the Most Probable Number (MPN) method. These results were confirmed with specific culture media and biochemical tests for fecal coliforms and E. coli. The samples were taken in the areas that are considered to be the most contaminated of the micro-basins, in the dry season and the rainy season. The water samples analyzed, corresponding to both seasons, did not show a significant statistical difference (p > 0.05) in the Most Probable Number. The high concentrations of coliforms and Escherichia coli were far from the standard for the quality of drinking water according to the COGUANOR standard of NMP < 2/100 mL, this is the only one available in the country on water and it was considered that it can be used for human consumption. With the beginning of the rainy season, the NMP for total coliforms and E. coli decreased, while for fecal coliforms a slight increase was observed. The micro-basin with the highest concentration was the Zanjón la Palín, with MPN values ​​between 3.5 x 1010/100 mL and 7.9 x 1010/100 mL, and the Chanquín River with the lowest degree of contamination, which recorded MPN values ​​of 3.3 x 104/100 mL. and 2 X 102/100 mL, although the high concentrations of total coliforms, fecal coliforms and E. coli quantified revealed that no micro-basin is suitable for developing any activity in them, whether recreational or agricultural. With the results obtained, it was clearly observed that there was discharge of wastewater to the micro-basins, and the contribution in this way to the eutrophication of the Basin and Lake Amatitlán. These findings were confirmed and correlated with the measurement of physicochemical parameters carried out simultaneously by the Authority for the Sustainable Management of the Basin and Lake Amatitlán (AMSA) in the micro-basins.